In molecular biology, cob(I)yrinic acid a,c-diamide adenosyltransferase (also known as ATP:cob(I)alamin or ATP:corrinoid adenosyltransferase) is an enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 which catalyses the conversion of cobalamin (vitamin B12) into its coenzyme form, adenosylcobalamin (coenzyme B12). Adenosylcobalamin (AdoCbl) is required for the ativity of certain enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

s. AdoCbl contains an adenosyl moiety liganded to the cobalt

Cobalt

Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....

 ion

Ion

An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

 of cobalamin via a covalent Co-C bond, and its synthesis is unique to certain prokaryotes. ATP:cob(I)alamin adenosyltransferases are classed into three groups: CobA-type, EutT-type and PduO-type. Each of the three enzyme types appears to be specialised for particular AdoCbl-dependent enzymes or for the de novo synthesis

De novo synthesis

De novo synthesis refers to the synthesis of complex molecules from simple molecules such as sugars or amino acids, as opposed to their being recycled after partial degradation. For example, nucleotides are not needed in the diet as they can be constructed from small precursor molecules such as...

 of AdoCbl. PduO and EutT are distantly related, sharing short conserved

Conserved sequence

In biology, conserved sequences are similar or identical sequences that occur within nucleic acid sequences , protein sequences, protein structures or polymeric carbohydrates across species or within different molecules produced by the same organism...

 motifs, while CobA is evolutionarily unrelated and is an example of convergent evolution

Convergent evolution

Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...

.

The CobA group includes the ATP:cob(I)alamin adenosyltransferases CobA (Salmonella typhimurium), CobO (Pseudomonas

Pseudomonas

Pseudomonas is a genus of gammaproteobacteria, belonging to the family Pseudomonadaceae containing 191 validly described species.Recently, 16S rRNA sequence analysis has redefined the taxonomy of many bacterial species. As a result, the genus Pseudomonas includes strains formerly classified in the...

 denitrificans), and ButR (Escherichia coli). There is a high degree of sequence

Sequence (biology)

A sequence in biology is the one-dimensional ordering of monomers, covalently linked within in a biopolymer; it is also referred to as the primary structure of the biological macromolecule.-See also:* Protein sequence* DNA sequence...

 identity between these protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

s. CobA is responsible for attaching the adenosyl moiety from ATP to the cobalt ion of the corrin

Corrin

Corrin is an heterocyclic compound. It is the parent macrocycle related to substituted derivative that is found in vitamin B12. Its name reflects that it is the "core" of vitamin B12 .-Coordination chemistry:...

 ring, necessary for the convertion of cobalamin to adenosylcobalamin. PduO functions to convert cobalamin to AdoCbl for 1,2-propanediol degradation

Chemical decomposition

Chemical decomposition, analysis or breakdown is the separation of a chemical compound into elements or simpler compounds. It is sometimes defined as the exact opposite of a chemical synthesis. Chemical decomposition is often an undesired chemical reaction...

, while EutT produces AdoCbl for ethanolamine

Ethanolamine

Ethanolamine, also called 2-aminoethanol or monoethanolamine , is an organic chemical compound that is both a primary amine and a primary alcohol . Like other amines, monoethanolamine acts as a weak base...

utilisation.